Highway Maintenance - IES Previous Year Questions

1. Which one of the following causes ravelling in bituminous pavement ?

[IES 1995]

  1. Excessive bitumen content
  2. Low bitumen content
  3. Use of open-graded aggregates
  4. Use of soft bitumen
Answer: Option C
Explanation:
  • The removal of materials from base course is called ravelling. Ravelling in bituminous pavements occurs when the base course is not covered with wearing course or when the wearing course is worn out completely.
  • Due to the fast moving vehicles plying on road, there is a suction caused between pneumatic tyres and the exposed base course material. This causes removal of binding material in WBM base and the stone aggregates are left in a loose state. Thus, in such a state, if the aggregates are open graded, it causes ravelling.

2. Assertion (A): Most flexible design procedures are based on Benkelman beam deflection measurements. 

Reason (R): Elastic deflection is a practical non-destructive measure of pavement stiffness which relates well to fatigue failure.

[IES 1996]

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not a correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Answer: Option D
Explanation:
Benkelman beam deflection method is used for
  • Evaluation of structural capacity of existing flexible pavements.
  • Estimation and design of flexible overlays for strengthening of any weak flexible pavement.
  • Measurement of deflection of flexible pavement under moving wheel loads.
The flexible design procedures are not based on Benkelman beam deflection measurement.

3.  Assertion (A): Bituminous roads disintegrate even with light traffic, but such road failures are not due to any wrong use of surface treatment.

Reason (R): Improper preparation of the subgrade and the foundation are responsible for this disintegration.

[IES 1997]

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not a correct explanation of A.
  3. A is true but R is false. 
  4. A is false but R is true.
Answer: Option C
Explanation:
Disintegration of bituminous roads occurs due to
  • Improper coating of bitumen over the surface of aggregates
  • Heavy rainfall
  • Heavy traffic
  • Improper bituminous mix design
Improper preparation of subgrade and foundation will not result in disintegration. But, it causes rutting or consolidation of the layers of flexible pavement.

4.  Match List-I (Pavement deficiency) with List-II (Explanation) and select the correct answer using the codes given below the lists:

List-I

  1. Bird baths
  2. Pot holes
  3. Ravelling
  4. Subsidence

List-II

  1. A step-sided, bowl shaped cavity caused by loss of surfacing as well as base course erosion. 
  2. Deformation which may be caused by localized or variable subgrade failure
  3. Irregular deformations which may be the result of differential settlement.
  4. Removal of larger surface aggregates leaving craters.
  5. Abrupt lowering of the road surface due to poor drainage.

[IES 1998]

Codes: A B C D

  1.  2  1  3  5
  2.  5  2 4  3
  3.  2  1  4  5
  4.  1  4  5  3
Answer: Option C
Explanation:
  • Birdbaths are deformation which may be caused by localized or variable subgrade failure.
  • Potholes are bowl shaped cavities caused by loss of surfacing as well as base course erosion.
  • Subsidence is the sinking of pavement surface because of underground material movement.
  • The removal of materials from base course is called ravelling.

5.  The corrected characteristic rebound deflection on a pavement, using Benkelman beam study is 2 mm. The equivalent granular overlay thickness required for an allowable deflection of 1 mm as per original IRC guidelines is _____ .

[IES 1999]

  1. 66 mm
  2. 133 mm
  3. 166 mm
  4. 33 mm
Answer: Option C
Explanation:
As per IRC,
Equivalent thickness of granular overlay, h0 = 550 log 10 (Dc/Da) mm
⇒ h0 = 550 log 10 (2/1)
⇒ h0 = 165.57 mm

6.  Consider the following: 

  1. LL of soil
  2. PL of soil
  3. SL of soil
  4. Annual average rainfall
  5. Temperature of the soil

As per the latest IRC guidelines, the set of essential data required to determine moisture correction factor of clayey subgrade soil in Benkelman beam study would include _____ .

[IES 1999]

  1. 1, 2, 3 and 4
  2. 2, 3 and 4
  3. 4 and 5
  4. 1, 2 and 4
Answer: Option D
Explanation:
Moisture correction factor depends on
  • Type of soil subgrade (i.e., clay or sand)
  • Plasticity Index of the soil (Plasticity Index = LL - PL)
  • Annual rainfall

7.  Which one of the following is useful in functional evaluation of pavement ?

[IES 2000]

  1. PSI
  2. PIEV
  3. Benkelman beam
  4. PCU
Answer: Option A
Explanation:
Present Serviceability Index (PSI) value is used for the functional evaluation of the pavements.

8.  Assertion (A): The prime coat is an interface bituminous treatment when the existing base course has a previous texture like water bound macadam.

Reason (R): The primer has to get into the capillary voids in the existing base and it should be of low viscosity. Bituminous emulsion is generally used as a prime coat.

[IES 2000]

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not a correct explanation of A.
  3. A is true but R is false. 
  4. A is false but R is true.
Answer: Option C
Explanation:
  • Prime coat is the application of a low viscous liquid bituminous material over an existing porous pavement surface like WBM base course. The main objective of applying a prime coat is to fill the capillary voids of the porous surface and to bond the loose mineral particles on the existing surface.
  • Usually MC or SC cutback bitumen of suitable viscosity is chosen depending on the porosity of the surface.

9.  Match List-I (Distress) with List-II (Meaning) and select the correct answer using the codes given below the lists:

List-I

  1. Settlement
  2. Subsidence
  3. Depression
  4. Distortion

List-II

  1. A localized, rather abrupt lowering of the road surface.
  2. A general lowering of the road surface.
  3. Irregular deformation of the road.
  4. Dished localized deformations.

[IES 2001]

Codes: A B C D

  1.  1  2  4  3
  2.  2  1  3  4
  3.  1  2  3  4
  4.  2  1  4  3
Answer: Option D
Explanation:
  • An abrupt lowering of the road surface is called as settlement.
  • Subsidence is the sinking of pavement surface because of underground material movement.
  • Depressions are localised deformations.

10.  On a National Highway pavement section, mean value of Benkelman beam deflection was obtained as 1.45 mm with standard deviation σ of 0.107 mm. Pavement temperature measured was 37°C and moisture correction was obtained as 1.6. What is the value of characteristic deflection considering the value of 2σ ?

[IES 2002]

  1. 2.69 mm
  2. 2.63 mm
  3. 1.94 mm
  4. 2.72 mm
Answer: Option B
Explanation:
Characteristic deflection, Dc = D + tσ = 1.45 + (2 x 0.107) = 1.664 mm
Since, the temperature is above 35°C,
Temperature correction = 0.0065 x (37 - 35) = 0.013
Thus, deflection after temperature correction = 1.664 - 0.013 = 1.651 mm
Hence, the corrected deflection for subgrade moisture = 1.651 x Moisture correction = 1.651 x 1.6 = 2.64 mm
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